Camera Exposure Value Calculator
Exposure value (EV) combines aperture and shutter time into a single logarithmic quantity, with an ISO adjustment when expressing the value at ISO 100. It helps compare settings, not determine the correct exposure for every scene.
How to use this calculator
- Enter the actual f-number, shutter denominator and ISO value.
- Check that units, denominator definitions and time periods are consistent before comparing scenarios.
- Run a second scenario when an assumption is uncertain.
Formula used by camera exposure value calculator calculator
EV100 = log₂(aperture² × shutter denominator) − log₂(ISO / 100).
- EV100 = log₂(aperture² × shutter denominator) − log₂(ISO / 100).
- Different combinations of aperture, shutter time and ISO can produce related exposure values but different motion blur, depth of field and noise.
- The tool performs arithmetic on the values entered and does not validate assumptions against outside records.
Worked examples
Worked example
f/8, 1/125 s and ISO 100.
EV100 = log₂(8² × 125) − log₂(100/100) ≈ 12.97.
The calculated exposure value at ISO 100 is shown.
Understanding the result
Exposure value (EV) combines aperture and shutter time into a single logarithmic quantity, with an ISO adjustment when expressing the value at ISO 100. It helps compare settings, not determine the correct exposure for every scene.
Different combinations of aperture, shutter time and ISO can produce related exposure values but different motion blur, depth of field and noise.
Important notes
Different combinations of aperture, shutter time and ISO can produce related exposure values but different motion blur, depth of field and noise.
Treat this output as an estimate tied to the stated inputs. For regulated, safety-critical, tax or professional decisions, verify applicable official guidance and specifications.
Frequently asked questions
Does the EV tell me whether an image is correctly exposed?
Not on its own; scene luminance and creative intent matter.
Why convert to ISO 100?
It provides a common reference for comparing exposures at different ISO settings.
How should I interpret the result?
Different combinations of aperture, shutter time and ISO can produce related exposure values but different motion blur, depth of field and noise.
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Related explanations
Learn the method behind the number or compare the terminology before using the calculator.
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This page provides a calculation tool plus explanatory information so you can understand what the result means and when the underlying method may not fit your situation.